Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
h,w=map(int,input().split())
A=[]
for i in range(h):
    A.append(list(input()))
kabe=0
for i in range(h):
    for j in range(w):
        if A[i][j]=="#":
            kabe+=1
def bfs():
    while queue:
        x,y,d=queue.pop()
        #print("xyd",x,y,d)
        for i in range(4):
            xx=x+dx[i] ; yy=y+dy[i]
            if xx==h-1 and yy==w-1:
                print(h*w-d-2-kabe);exit()
            if 0<=xx<h and 0<=yy<w and A[xx][yy]==".":
                A[xx][yy]="#"
                queue.appendleft([xx,yy,d+1])


from collections import deque
dx=[-1,0,1,0] ;dy=[0,1,0,-1]
queue=deque([[0,0,0]])
bfs()
print(-1)